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On a global scale, a radical transformation of the healthcare sector is taking place right before our eyes. The last few years have become a turning point in terms of the number of new directions, the emergence of innovative diagnostic and treatment methods, and the introduction of digital platforms. Digital medicine uses information and communication technologies to address the numerous problems associated with ensuring the quality and accessibility of medical care already available today. The rapid development of neural networks and artificial intelligence (AI) provides doctors with ample opportunities to predict the course of diseases and calculate the risks to the health of patients. Manufacturers of medical devices offer consumer a wide range of software and products with AI embedded. Despite the tremendous advances in the application of AI in medicine, the medical community is highly concerned about some of the intractable problems associated with the too rapid and ubiquitous use of these digital platforms. A highly trained neural network is an extremely complex computer program consisting of a large number of internal hidden layers with customizable parameters. The more complex the neural network and the number of computational operations it performs, the more difficult it is to understand the processes in its inner layers. The functioning of AI systems in a black box format makes explaining the results of its work a very non-trivial task. Therefore, in the future, research will certainly be required assessing the reliability of these systems and interpreting their decision-making processes which, will affect the neural networks of the latest generations.

The coronavirus pandemic has caused adjustments to be made to the organization of medical care for the population worldwide. The reorganization of medical institutions to provide emergency, outpatient, and inpatient medical care to infected patients required huge financial and personnel costs and caused a kind of bias towards reducing the medical services provided to patients with chronic non-infectious diseases, which in turn determine the main levels of morbidity, premature mortality, and disability of the population. The availability of medical care to patients with chronic non-infectious diseases has decreased in all the countries that were impacted by COVID-19. This situation has not gone unnoticed by the medical community and as a result, various ways to overcome this problem have been proposed. The proposed article presents an analytical review of various types of Russian and foreign medical sources including articles, orders, statements, interviews, and surveys devoted to the problem of addressing the availability of various types of medical care. The review presents the most obvious and widespread problems in public health during the pandemic. It also analyzes the methods used in various countries, including Russia, to overcome the decline in the availability of medical care. The wide range of problems described that arose in domestic and foreign healthcare during the COVID-19 pandemic, and the variety of ways to solve them, allow us to conclude that this study is relevant. A literary review of articles (reviews, original research, interview data, and telephone surveys) published from March 2020 to March 2022 was conducted on the impact of the COVID-19 pandemic on the availability of medical care for somatic patients in the Russian Federation and several foreign countries. The methods of bibliographic, informational and semantic search for sources in Google Scholar, PubMed and Scopus databases were used. A system analysis of the sources was performed.

BACKGROUND: This article is devoted to the impact of the digitalization of modern healthcare on the nature of relationships between a doctor and a patient. AIM: To assess the level of readiness of the patients in the city hospital for the introduction of digital technologies in the system of providing medical services. MATERIALS AND METHODS: The study was based on the results of a questionnaire survey of 154 patients in city hospitals in JulyAugust 2022 in Nizhny Novgorod. The survey questions included studying the use by modern day patients of various methods of digital communication with medical workers, the impact of the availability of medical information on the internet on the level of patients trust on a doctor, and patients opinions about the prospects for solving problems of modern healthcare through digitalization. RESULTS: The results of the survey revealed that 104 (67.5%) patients do not use digital communications, and 94 (61%) have no intention of using them. Among the prospects for the use of digital technologies in healthcare, the most popular for respondents were getting referrals for medical services (n=83, 53.9%), a prescription (n=57, 37%), and documents certifying temporary disability (n=43, 27, 9%). Only 8 (5.2%) respondents systematically check the diagnoses and prescriptions received from the attending physician on the internet and 25 (16.2%) do this from time to time. Only 2 (1.3%) respondents stated that they have a priority level of trust in recommendations from internet sources, and the rest of the patients trust their real attending physicians more. CONCLUSION: A modern patient seeks to receive medical care in real contact with a doctor, considering digital technologies mainly as a tool that addresses formal issues that arise when visiting medical organizations.

On a global scale, a radical transformation of the healthcare sector is taking place right before our eyes. Health care systems in many countries are changing at an incredible pace under the pressure of innovative digital platforms that have gained popularity under the names of artificial intelligence (AI) and machine learning (ML). AI systems, powered by massive amounts of data collected from everywhere, are able to guarantee optimal decision making for key players in the healthcare industry, from the pharmaceutical industry to the smallest healthcare providers. This article presents the results of the analysis of achievements and prospects for the use of innovative digital technologies and platforms in modern health care. According to international experts in medicine, it is possible to automate 36% of functions, primarily at the levels of data collection and analysis, and the use of AI technologies can significantly increase the gross profit of firms and organizations in relation to medical activities. There is no doubt about this since information has already become the main driver of management across all sectors of the global economy in general and in the health care sector in particular. The main motivations for the penetration of AI into health care are the escalating costs and the urgent need to limit them, the problem of poor-quality diagnostics (up to 30% of ongoing studies turn out to be unreliable or are misinterpreted) and the desire for standardization and automation of routine functions up to the creation of self-managed diagnostic models. However, the biggest challenge for AI in healthcare is not whether these technologies will be useful enough, but how to ensure that they are quickly and efficiently implemented in everyday clinical practice.

The paper discusses the use of methane (generated in the process of oxygen recovery from carbon dioxide released by the crew during its hydrogenation in the Sabatier reaction, with subsequent extraction of 61% of oxygen through electrolysis of the resultant water) in a regenerative life support system for crews on space missions. It demonstrates that the methane resulting from Sabatier reaction can be used both for pyrolysis in order to return the resulting hydrogen into this reaction so as to extract 100% of oxygen from carbon dioxide, and for producing food protein for life support in space. The use of methane pyrolysis was enabled by new technologies which allowed lowering the process temperature down to 500–700°C and obtaining the easy-to-remove carbon. It provides recommendations for designing space systems for methane pyrolysis. The paper makes the case for use of the existing processes for industrial production of protein from methane using methanotrophic bacteria in the production of food protein for space food rations, determines the balance of a closed-loop methanotrophic reaction, provides calculation basis and recommendations for designing space systems for methanotrophic production of food protein. Development of a system for food protein production from methane will enable its use as one of the systems for providing food on the Moon and Mars, as well as a backup system in space transportation missions. Key words: space missions, crew life support, СО2 hydration, methane pyrolysis, methanotrophic bacteria, food protein.

The paper presents partial analytical solutions for equations describing variation in trace amounts of carbon dioxide in the atmosphere of habitable spaces within pressurized modules (PM) of a space station. The solutions may find practical application in calculations of concentrations for any contaminants, or for air flow through the purification system. It is shown that in a case where low-toxic contaminants are released into the PM atmosphere, it would be enough to cycle 3 volumes of the PM air through the purification system when the system operates without the breakthrough concentration (without the residual concentration of the contaminant at the outlet from the purification system), in order to achieve the 95% purification of the atmosphere. For highly toxic contaminants this value should be significantly increased depending on the maximum allowable concentration of the substance (47 volumes and more — up to 99.9% purification). The paper also considers variation in the concentration of the contaminant in the atmosphere during intermixing of atmospheres between PMs using intermodular ventilation. As a result, new analytical solutions were obtained for practical calculations which make it possible to determine gaseous contaminant concentration at any point in time and the time of the final equalization of the contaminant concentration in the space station atmosphere. It was determined that the time needed for complete mixing of gaseous contaminants through intermodular ventilation between two PMs does not depend on the initial concentrations of the contaminants (and only depends on the PM volumes and the intermodular ventilation flow rate). Key words: space station, pressurized module atmosphere, carbon dioxide, atmosphere purification, variation in concentration, air flow, atmosphere mixing.

The paper presents partial analytical solutions for equations describing variation in trace amounts of carbon dioxide in the atmosphere of habitable spaces within pressurized modules (PM) of a space station. The solutions may find practical application in calculations of concentrations for any contaminants, or for air flow through the purification system. It is shown that in a case where low-toxic contaminants are released into the PM atmosphere, it would be enough to cycle 3 volumes of the PM air through the purification system when the system operates without the breakthrough concentration (without the residual concentration of the contaminant at the outlet from the purification system), in order to achieve the 95% purification of the atmosphere. For highly toxic contaminants this value should be significantly increased depending on the maximum allowable concentration of the substance (47 volumes and more — up to 99.9% purification). The paper also considers variation in the concentration of the contaminant in the atmosphere during intermixing of atmospheres between PMs using intermodular ventilation. As a result, new analytical solutions were obtained for practical calculations which make it possible to determine gaseous contaminant concentration at any point in time and the time of the final equalization of the contaminant concentration in the space station atmosphere. It was determined that the time needed for complete mixing of gaseous contaminants through intermodular ventilation between two PMs does not depend on the initial concentrations of the contaminants (and only depends on the PM volumes and the intermodular ventilation flow rate). Key words: space station, pressurized module atmosphere, carbon dioxide, atmosphere purification, variation in concentration, air flow, atmosphere mixing.

This article assesses the radiological environment at the nuclear site of the Mayak PA, Russian Federation, during and after the accident in 1957, the so-called 'Kyshtym Accident', and the radiation doses to those who participated in the eradication of its consequences. Based on numerous archival documents, this paper presents the radiation data for 1957-1960, including individual dosimetry monitoring data and estimated doses to the Mayak workers, as well as the to personnel in supporting organisations and the military involved in the remediation operations. From 1957-1959 some 38 500 individuals took part in the clean-up actions and remediation of contaminated areas of the Mayak PA industrial site after the accident, including individuals exposed at the time of the accident: Mayak PA employees, militarypersonnel, and civil construction workers. External equivalent doses to 10 500 individuals were estimated in the range of 220 to 265 mSv, while there were cases of doses up to 950 mSv and higher. The collective dose received during the accident and its aftermath was in the region of 7300 person-Sv. By October-December 1957, the collective dose was about 4500 person-Sv. Collective doses recorded in 1958 and 1959 amounted to 2250 person-Sv and 480 person-Sv, respectively.

The International Commission on Radiological Protection (ICRP) has embarked on a review and revision of the system of Radiological Protection that will update the 2007 general recommendations in ICRP Publication 103. This is the beginning of a process that will take several years, involving open and transparent engagement with organisations and individuals around the world. While the system is robust and has performed well, it must adapt to address changes in science and society to remain fit for purpose. The aim of this paper is to encourage discussions on which areas of the system might gain the greatest benefit from review, and to initiate collaborative efforts. Increased clarity and consistency are high priorities. The better the system is understood, the more effectively it can be applied, resulting in improved protection and increased harmonisation. Many areas are identified for potential review including: classification of effects, with particular focus on tissue reactions; reformulation of detriment, potentially including non-cancer diseases; re-evaluation of the relationship between detriment and effective dose, and the possibility of defining detriments for males and females of different ages; individual variation in the response to radiation exposure; heritable effects; and effects and risks in non-human biota and ecosystems. Some of the basic concepts are also being considered, including the framework for bringing together protection of people and the environment, incremental improvements to the fundamental principles of justification and optimisation, a broader approach to protection of individuals, and clarification of the exposure situations introduced in 2007. In addition, ICRP is considering identifying where explicit incorporation of the ethical basis of the system would be beneficial, how to better reflect the importance of communications and stakeholder involvement, and further advice on education and training. ICRP invites responses on these and other areas relating to the review of the System of Radiological Protection.

This chapter deals with different characteristics of high-voltage power lines as media for HF signal transmission including mechanical construction, number of circuits, effects of reflected waves, transpositions, tap lines, and transit substations. It shows that weather conditions have dramatically impact on the parameters of HF path attenuation and noise especially when ice coating occurs. It contents information about features of PLC channels’ construction over underground power cables and mixed cable-overhead power lines. The purpose of this chapter is to consider features of frequency dependences the most interesting for the reader HF path parameters and disturbances present in these paths.

In this chapter, designing of digital PLC channels including consistent solution of a certain set of tasks which ultimately would allow ensuring reliability of the communication channel is discussed. Main topic relates to selection of appropriate frequency bands to provide high reliable channel. It presents original approach for selection of maximum allowable frequency in criteria of required attenuation margin and signal-to-noise ratio for the DPLC channel with bit rate adaptation. In final part, examples of long-term DPLC channel parameters monitoring during foul weather are presented.

If DPLC equipment modems are the main part of the system and are responsible for how information will be transmitted through a HF path, then multiplexers are responsible for transmitting/receiving information signals between user interface modules and modem. Multiplexers perform functions of aggregation of user interface signals, their prioritization, and routing in transit connections. Multiplexers interact with network elements used for connecting DPLC equipment and various network equipment: Ethernet switches and IP routers. Multiplexers also compress the speech signals of voice modules using low bit rate speech codecs. This chapter presents approaches of application of multiplexors as part of the DPLC equipment, voice and data signal prioritization, and transit connections. It observes technologies, which are applied in network devices for IP/Ethernet traffic transmission and propose different variants of application of DPLC systems in IP networks.

This chapter considers the DPLC equipment as the digital transmission system with characteristics adapted to work along high-voltage power lines. It observes what technologies and methods of digital modulation, encoding, channel equalization and echo cancelation are used in modern DPLC systems and what the main characteristics of DPLC equipment modems are. It summarizes main parameters of DPLC systems – spectral efficiency, achievable bit rate, bit rate adaptation, and latency. The comparison between single-carrier and multicarrier modems and an introduction in the newest wideband digital power line carrier are given.

In this work we presented development results for monocrystalline silicon macrosamples with porous silicon area. The area ensures mechanical impact stability. It is identified that there is the crack resistance increase of porous silicon in comparison with monocrystalline silicon during indentation. Porous structure parameters are defined as well. The macrosamples were used as carriers of anticancer drugs. The developed macrosamples’ design was used as an anticancer drug carrier during the development of method for in vitro effectiveness assessment of drug behavior. The example of Doxorubicin usage shows that designed carriers ensure prolonged dosed influence of drugs on cancer cells.

In the first years of its operation, the Mayak Production Association, a facility part of the Soviet nuclear weapons program in the Southern Urals, Russia, discharged large amounts of radioactively contaminated effluent into the nearby Techa River, thus exposing the people living at this river to external and internal radiations. The Techa River Cohort is a cohort intensely studied in epidemiology to investigate the correlation between low-dose radiation and health effects on humans. For the individuals in the cohort, the Techa River Dosimetry System describes the accumulated dose in human organs and tissues. In particular, organ doses from external exposure are derived from estimates of dose rate in air on the Techa River banks which were estimated from measurements and Monte Carlo modelling. Individual doses are calculated in accordance with historical records of individuals' residence histories, observational data of typical lifestyles for different age groups, and age-dependent conversion factors from air kerma to organ dose. The work here describes an experimentally independent assessment of the key input parameter of the dosimetry system, the integral air kerma, for the former village of Metlino, upper Techa River region. The aim of this work was thus to validate the Techa River Dosimetry System for the location of Metlino in an independent approach. Dose reconstruction based on dose measurements in bricks from a church tower and Monte Carlo calculations was used to model the historic air kerma accumulated in the time from 1949 to 1956 at the shoreline of the Techa River in Metlino. Main issues are caused by a change in the landscape after the evacuation of the village in 1956. Based on measurements and published information and data, two separate models for the historic pre-evacuation geometry and for the current geometry of Metlino were created. Using both models, a value for the air kerma was reconstructed, which agrees with that obtained in the Techa River Dosimetry System within a factor of two.

This article discusses the characteristics of high voltage power line carrier channels over underground cables and mixed cable-overhead high voltage power lines. It shows which modal parameters underground cables have and how junctions of overhead power lines with power cables influences to the parameters of PLC channel. The most difficult and interesting scenario when underground cable has sheaths transpositions or/and sheaths earthling at one end of the line is covered.

Luminescence dosimetry was performed using bricks from the former settlement of Metlino, Southern Urals, Russia, to investigate the feasibility of validating the Techa River Dosimetry System (TRDS) 2016 for the shore of the Metlinsky Pond, upper Techa River region. TRDS is a code for estimating external and internal doses for members of the Extended Techa River Cohort. Several brick samples were taken from the north-western wall of the granary, facing the Metlinsky Pond. Samples were measured at different heights and at different depths into the bricks. Dating of the granary was performed by analyzing well shielded bricks. Assessment of the gamma dose-rate at the sample positions was done by thermoluminescent dosimeters and the dose-rate in front of the granary mapped with a dose-rate meter. Anthropogenic doses in bricks vary from 0.8 to 1.7 Gy and show an increase with sampling height. A similar height profile is observed for the current gamma dose-rate, which is compatible with the results of the dose-rate mapping. Implications for validating the TRDS are discussed.

This paper deals with fabrication and characterization of liquid flow sensor based on electrokinetic effect – streaming potential. The possibility of using silicon microchannel membrane as a sensing element of the sensor has been demonstrated. Electric response of the sensor has been determined by passing deionized water through the membrane. A linear dependence of the operating characteristic has been found. Sensitivity and performance of the electrokinetic device have been evaluated. The optimal design of the liquid flow sensor has been proposed

The estimation of plutonium fetal transfer and the calculation of individual in utero and postnatal doses for the Mayak Production Association (PA) offspring cohort.The model developed by the International Commission on Radiological Protection (ICRP) for the transfer of plutonium to the fetus following maternal intakes before and during pregnancy has been adjusted for application to analysis of the fetal transfer of (239)Pu for Mayak workers. Improved estimates of fetal to maternal concentration ratios (CF:CM) have been obtained based on a correlation observed between adult offsprings' measured daily urine (239)Pu activity and estimates of their mothers' systemic activity at conception. Data on (239)Pu activity in daily urine samples were collected from 13 selected adults whose mothers worked at the Mayak PA facility during the period from 1948-1953, before and/or during pregnancy.A comparison of measured and modeled excretion data enabled a mean value of 0.18 ± 0.02 (n = 21) to be inferred for the Pu CF:CM ratio, with a coefficient of variation of 60%.Point estimates of the individual in utero and postnatal absorbed doses for the red bone marrow and liver were in the range 2…13 mGy in 95% of the cases for the cohort of 1936 offspring.

The development of the AIRS (EOS/Aqua) and IASI (MetOp) satellite hyperspectral IR sounders opens new opportunities for determining the average tropospheric carbon dioxide concentration (\(X_{CO_2 } \)) and total methane content (\(Q_{CH_4 } \)) in the atmosphere from large distances, which is important in climatic studies and since the ground network for CO2 and CH4 observations is scarce. The improved scheme for \(X_{CO_2 } \) retrieval from the AIRS data, which was used to construct the \(X_{CO_2 } \) spatial distribution based on the AIRS data for July 2003 and 2010 covering Siberia, is presented. A similar methodology was also used to retrieve instantaneous \(X_{CO_2 } \) values from the cloud-cleared IASI data for July 7, 2008 and the YAK-AEROSIB experimental region. A comparison of the satellite data with quasi-synchronous aircraft observations gives an error of about 2.2 million−1. The iterative physical algorithm was developed in order to retrieve \(Q_{CH_4 } \). The efficiency of the proposed algorithm was estimated during the experiments with actual IASI data covering the Siberian region during several days in July 2008. The \(Q_{CH_4 } \) estimates were validated by comparing them with the spatially superimposed and quasi-synchronous \(Q_{CH_4 } \), estimates based on the AIRS data. The standard deviations of both types of estimates are not more than 3%.

The purpose of this study was to obtain quantitative data on plutonium microdistribution in different structural elements of human bone tissue for local dose assessment and dosimetric models validation. A sample of the thoracic vertebra was obtained from a former Mayak worker with a rather high plutonium burden. Additional information was obtained on occupational and exposure history, medical history, and measured plutonium content in organs. Plutonium was detected in bone sections from its fission tracks in polycarbonate film using neutron-induced autoradiography. Quantitative analysis of randomly selected microscopic fields on one of the autoradiographs was performed. Data included fission fragment tracks in different bone tissue and surface areas. Quantitative information on plutonium microdistribution in human bone tissue was obtained for the first time. From these data, the quantitative relationships of plutonium decays in bone volume to decays on bone surface in cortical and trabecular fractions were defined as 2.0 and 0.4, correspondingly. The measured quantitative relationship of decays in bone volume to decays on bone surface does not coincide with recommended models for the cortical bone fraction by the International Commission on Radiological Protection. Biokinetic model parameters of extrapulmonary compartments might need to be adjusted after expansion of the data set on quantitative plutonium microdistribution in other bone types in humans as well as other cases with different exposure patterns and types of plutonium.

Epidemiological studies of the relationship between risk and internal exposure to plutonium are clearly reliant on the dose estimates used. The International Commission on Radiological Protection (ICRP) is currently reviewing the latest scientific information available on biokinetic models and dosimetry, and it is likely that a number of changes to the existing models will be recommended. The effect of certain changes, particularly to the ICRP model of the respiratory tract, has been investigated for inhaled forms of (239)Pu and uncertainties have also been assessed. Notable effects of possible changes to respiratory tract model assumptions are (1) a reduction in the absorbed dose to target cells in the airways, if changes under consideration are made to the slow clearing fraction and (2) a doubling of absorbed dose to the alveolar region for insoluble forms, if evidence of longer retention times is taken into account. An important factor influencing doses for moderately soluble forms of (239)Pu is the extent of binding of dissolved plutonium to lung tissues and assumptions regarding the extent of binding in the airways. Uncertainty analyses have been performed with prior distributions chosen for application in epidemiological studies. The resulting distributions for dose per unit intake were lognormal with geometric standard deviations of 2.3 and 2.6 for nitrates and oxides, respectively. The wide ranges were due largely to consideration of results for a range of experimental data for the solubility of different forms of nitrate and oxides. The medians of these distributions were a factor of three times higher than calculated using current default ICRP parameter values. For nitrates, this was due to the assumption of a bound fraction, and for oxides due mainly to the assumption of slower alveolar clearance. This study highlights areas where more research is needed to reduce biokinetic uncertainties, including more accurate determination of particle transport rates and long-term dissolution for plutonium compounds, a re-evaluation of long-term binding of dissolved plutonium, and further consideration of modeling for plutonium absorbed to blood from the lungs.

Lung cancer mortality among 5,058 male workers of the Mayak Production Association has been analyzed with emphasis on the interaction of smoking and radiation exposure by using the two-step clonal expansion (TSCE) model of carcinogenesis. The cohort consists of all Mayak workers with known smoking status, who were employed in the period 1948-1972, and who either had the plutonium concentration in urine measured or who worked in the reactors, where plutonium exposure was negligible. Those who died during the first two years after the first urine sampling were excluded. The follow-up extended until the end of 1998. During this time, 2,176 workers died, including 244 lung cancer cases. Mayak workers were exposed to external (gamma and neutron) radiation, and in the radiochemical and plutonium plants to plutonium. In the preferred TSCE model, internal radiation and smoking act on the clonal expansion of pre-carcinogenic clones. Assuming a plutonium radiation weighting factor of 20, the excess relative risk per lung dose was estimated to be 0.11 (95% CI: 0.08; 0.17) Sv(-1). Most of the lung cancer deaths are found to be due to smoking. The second main factor is the interaction of smoking and internal radiation. The model is sub-multiplicative in relative risks due to smoking and radiation. In a multiplicative version of the TSCE model, internal radiation acts on initiation and transformation rates. This model version agrees with conventional epidemiological risk models, because it also suggests a higher risk estimate than the preferred TSCE model. However, it fits the data less well than the preferred model.

Two forms of complement-depleting cobra venom factor (CVFm1 and CVFm2), possessing molecular masses of 142.6 kDa (CVFm1) and 143.1 kDa (CVFm2), according to MALDI mass-spectrometry, were isolated from the Naja melanoleuca cobra venom. As shown by polyacrylamide gel electrophoresis in the presence of SDS, both forms similarly to factor from the Naja kaouthia cobra venom (CVFk) consist of three polypeptide chains with molecular masses of about 70, 50, and 30 kDa, the two large subunits being glycosylated. As determined by MALDI mass-spectrometry, 30 kDa subunits of CVFm1 and CVFm2 have considerably different finger-prints of tryptic digests that suggests differences in their amino acid sequences. A study of activity in vivo has shown no significant differences in C3 consumption by CVFm1, CVFm2 and CVFk in mouse blood. However, as shown by an immunoassay method, they differ in their ability to activate the complement system via C3 conversion, the ratio of these activities for CVFm1:CVFm2:CVFk being 2.5:1.6:1. Kinetic studies using a hemolytic test showed that complement depletion by CVFm1 is faster than that by CVFm2. Thus, for the first time the presence in a single venom of two forms of CVF differing by both amino acid sequence and biological activity has been shown.

Osteosarcomas occur from exposures to bone-seeking, alpha-particle-emitting isotopes, particularly plutonium. The skeletal distribution of putative 239Pu-induced osteosarcomas reported in Mayak Metallurgical and Radiochemical Plutonium Plant workers is compared with those observed in canine studies, and these are compared with distributions of naturally occurring osteosarcomas in both species. In the Mayak workers, 29% and 71% of the osteosarcomas were in the peripheral and central skeleton, respectively, with the spine having the most tumors (36%). An almost identical distribution of plutonium-induced osteosarcomas was reported for dogs injected with 239Pu as young adults. This distribution of osteosarcomas is quite different from the distributions of naturally occurring osteosarcomas for both species. In the Cooperative Osteosarcoma Study Group in humans (1,736 osteosarcomas from all ages), over 91% of the tumors occurred in the peripheral skeleton. In the Mayo Clinic group of older individuals (40 years old), over 60% of the osteosarcomas appeared in the peripheral skeleton. The distribution of naturally occurring osteosarcomas in the canine is similar to that in the adult human. The similarities of the distributions of plutonium-associated osteosarcomas in the Mayak workers with those found in experimental studies suggest that many of the reported osteosarcomas may have been associated with plutonium exposures. These results also support the experimental paradigm that plutonium osteosarcomas have a preference for well vascularized cancellous bone sites. These sites have a greater initial deposition of plutonium, but also greater turnover due to elevated bone remodeling rates.

At present, direct data on risk from protracted or fractionated radiation exposure at low dose rates have been limited largely to studies of populations exposed to low cumulative doses with resulting low statistical power. We evaluated the cancer risks associated with protracted exposure to external whole-body gamma radiation at high cumulative doses (the average dose is 0.8 Gy and the highest doses exceed 10 Gy) in Russian nuclear workers. Cancer deaths in a cohort of about 21,500 nuclear workers who began working at the Mayak complex between 1948 and 1972 were ascertained from death certificates and autopsy reports with follow-up through December 1997. Excess relative risk models were used to estimate solid cancer and leukemia risks associated with external gamma-radiation dose with adjustment for effects of plutonium exposures. Both solid cancer and leukemia death rates increased significantly with increasing gamma-ray dose (P0.001). Under a linear dose-response model, the excess relative risk for lung, liver and skeletal cancers as a group (668 deaths) adjusted for plutonium exposure is 0.30 per gray (P0.001) and 0.08 per gray (P0.001) for all other solid cancers (1062 deaths). The solid cancer dose-response functions appear to be nonlinear, with the excess risk estimates at doses of less than 3 Gy being about twice those predicted by the linear model. Plutonium exposure was associated with increased risks both for lung, liver and skeletal cancers (the sites of primary plutonium deposition) and for other solid cancers as a group. A significant dose response, with no indication of plutonium exposure effects, was found for leukemia. Excess risks for leukemia exhibited a significant dependence on the time since the dose was received. For doses received within 3 to 5 years of death the excess relative risk per gray was estimated to be about 7 (P0.001), but this risk was only 0.45 (P = 0.02) for doses received 5 to 45 years prior to death. External gamma-ray exposures significantly increased risks of both solid cancers and leukemia in this large cohort of men and women with occupational radiation exposures. Risks at doses of less than 1 Gy may be slightly lower than those seen for doses arising from acute exposures in the atomic bomb survivors. As dose estimates for the Mayak workers are improved, it should be possible to obtain more precise estimates of solid cancer and leukemia risks from protracted external radiation exposure in this cohort.

The effect of scattering of different multiplicity on polarization characteristics of scattered light is studied by the Monte Carlo computer simulation technique. The scattering multiplicity distribution versus the direction of scattering and dimensions of the scattering system is obtained for monodisperse systems of spherical particles of different size. The angular dependences of the elements of the light-scattering matrix (LSM) are calculated. It is shown that in a system of spherical particles, specific features of the LSM structure associated with multiple scattering have much in common with similar features of the LSM in systems of nonspherical particles under conditions of single scattering. The angular dependences of the degree of depolarization of the scattered light are studied.

For more than 25 years, the United States Transuranium and Uranium Registries (USTUR) and the Dosimetry Registry of the Mayak Industrial Association (DRMIA) of the Russian Federation have, each independently, collected tissues at autopsy from workers with potential or confirmed body burdens of actinide elements resulting from occupational exposures. Tissues, thus obtained, were radiochemically analyzed for actinides for the purpose of evaluating the biokinetics of these elements in the human body. Scientists of these two organizations have recently begun a collaborative research program to compare, combine and analyze the data to verify or refine biokinetic models needed for radiation dosimetry.

Lung cancer mortality was analyzed among 4279 nuclear workers of the Mayak facilities in the former Soviet Union, who were exposed to chronic irradiation both externally and internally from incorporated plutonium. The analysis was carried out in terms of a relative risk model. It was shown that an earlier estimate of the excess relative risk for lung cancer, that exceeds the value employed by ICRP by a factor of roughly 2, as well as an earlier estimated latency period of 24 years for lung cancer induction were the result of the numerical procedure chosen. In another recently published case control study, a purely quadratic, threshold-type dose response to incorporated plutonium was deduced. In the present calculations, no evidence for a departure from linearity in dose response was suggested. Principal aim of this study has been the comparison to methods used in the earlier cohort analysis. More detailed risk modelling on the basis of the most recent follow-up will be required.

This paper has been devoted to a creation of flow-through sensor based on ordered macroporous silicon for electrophysical detection of liquids. Interactions of sensor with different liquids (deionized water, ethyl alcohol and sodium tetraborate in various concentrations) were studied by high frequency conductance measurements. It was established that the sensor had specific response for each liquid. It was shown that the proposed electrophysical method allowed identifying the liquid flowing through the sensor.

A preliminary study is reported comparing two research programmes for the analysis of actinide elements in human tissues, the Dosimetry Registry of the Mayak Industrial Association (DRMIA), Russian Federation, and the United States Transuranium and Uranium Registries (USTUR), to determine the intercomparability of data collected by the two Registries. Both Registries have been in operation for nearly the same period of time and each has a collection of dosimetric, medical, and autopsy tissue radioanalysis data for occupationally exposed workers from plutonium production facilities in their country. A comparison of selected data from those collected by the two Registries, liver and skeletal concentrations as a function of time between exposure and death of the autopsy subjects, indicates close compatibility of data. Median liver concentrations of DRMIA cases were 240 times higher than those of USTUR cases. The relative concentrations of plutonium in the skeletons and livers with time after exposure appear to be the same in both groups and this implies that the analytical results were comparable over a wide range of times after exposure and exposure levels.